Reversible Subclinical Hypothyroidism in the Presence of Adrenal Insufficiency

Abstract and Introduction

Abstract

Objective: To describe 3 different scenarios of reversible hypothyroidism in young patients with adrenal insufficiency.
Methods: We present 3 case reports of patients with adrenal insufficiency—one with delayed puberty, the second with type 1 diabetes and poor weight gain, and the third with hypoglycemia-related seizures and glucocorticoid deficiency—who had biochemical evidence of hypothyroidism.
Results: Our first patient (case 1) initially had a mildly elevated thyrotropin (thyroid-stimulating hormone or TSH) level and a normal free thyroxine (FT₄) level that, on follow-up assessment, had progressed to persistent mild elevation of TSH and low FT₄ concentration. The other 2 patients (cases 2 and 3) had low FT₄ and mildly elevated TSH values at the time of diagnosis of adrenal insufficiency. In all 3 patients, the results of thyroid function tests normalized with use of physiologic doses of adrenal hormone replacement therapy, without thyroid hormone replacement. All 3 patients remained euthyroid after 4, 3, and 1 year of follow-up, respectively.
Conclusion: These observations add insights into the complexities of the thyroadrenal interactions. These examples are important because thyroid hormone replacement in the setting of adrenal insufficiency could be unwarranted.

Introduction

Borderline elevations of thyrotropin (thyroid-stimulating hormone or TSH) sometimes associated with minimally depressed levels of free thyroxine (FT₄) are common findings during assessment of patients with an array of complaints.^[1] Often (rightly or wrongly), these laboratory features are ignored because of their subtlety. In light of the relative abundance of cases of mild hypothyroidism,^[1,2] we thought that our experience with 3 cases of TSH elevation in children with newly diagnosed adrenal insufficiency might be informative. Endocrinologists continue to debate what constitutes an elevated TSH level^[3] and when such a finding should be treated. On the basis of the 2002 clinical practice guidelines from the American Association of Clinical Endocrinologists,^[4] an elevated TSH value that is below 10 µIU/mL and that is associated with a normal FT₄ level can be monitored without initiation of thyroid hormone replacement therapy, except during pregnancy. In patients with both hypothyroidism and adrenal insufficiency, adrenal crisis can be precipitated if thyroid hormone replacement is instituted before the initiation of corticosteroid therapy.^[5] In this report, we describe 3 young patients in whom mild hypothyroidism was detected but who, in fact, had severe adrenal insufficiency. More interestingly, the thyroid state normalized solely by treatment of the adrenal insufficiency.

Endocr Pract. 2006;12(5):572-575. © 2006  American Association of Clinical Endocrinologists